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Some email fails to arrive. &nbsp;Sender gets &quot;Undeliverable&quot; notice with the folowing message:<br />
Action: failed<br />
Diagnostic-Code: smtp; Incomplete SMTP session (cause: idle timeout)<br />
Status: 5.0.0
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</div>


Some email fails to arrive.  Sender gets "Undeliverable" notice with the folowing message:
Action: failed
Diagnostic-Code: smtp; Incomplete SMTP session (cause: idle timeout)
Status: 5.0.0

Delivery Failed

Interactions between email servers and clients are governed by email protocols. The three most common email protocols are POP, IMAP and MAPI. Most email software operates under one of these (and many products support more than one).  The correct protocol must be selected, and correctly configured, if you want your email account to work.

Email Protocols

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.